The present invention relates generally to aviation agrichemical application. More particularly the present invention relates to a low-cost, high efficiency, replacement type aircraft spray boom valve assembly.
Spray booms or manifolds of the type contemplated by the present invention are usually secured to the wings of the airplane through a variety of mounting systems. Such mounting systems may include clamps of the type disclosed in my co-pending patent application, Ser. No. 310,463 now U.S. Pat. No. 4,445,657 Filed 10/31/81, and entitled Spray Boom Mounting Assembly. As will be appreciated by those skilled in the art, the various forms of hardware including manifolds, fluid lines, spray booms, valves, nozzles and the like used in conjunction with airborne agri-chemical application generates an extreme variety of mechanical and chemical stresses. Due to the corrosive chemicals involved, rapid deterioration of metal parts may occur and such deterioration is particularly deleterious in conjunction with the spray nozzles through which agri-chemicals must be outputted for application.
Due to a variety of Federal regulations, including EPA regulations and rules, for example, pesticides, insecticides and other agri-chemicals must be handled and/or applied according to various detailed and vexatious procedures.
It therefore may be important that a spray system used in conjunction with airborne spray booms, for example, be readily locked to a fail-safe position under certain circumstances. By way of example, such a circumstance includes the long-distance travel of a crop-duster plane to a remote job site etc. It is very important that no pesticides or the like be inadvertently dropped upon unintended areas. Moreover, because of the corrosive nature of typical agri-chemicals, and their negative effects upon metallic components, equipment employed in conjunction with agrichemical application must be thoroughly cleaned and rinsed after an opertion. Cleaning is necessary to prevent subsequent chemical reactions from degrading or oxidizing critical working parts. It is important to wash away residue of various chemicals to prevent jamming of critical moving parts.
A variety of prior art spray boom ejector valves may be releasably fitted to spray booms, manifolds or the like. Conventionally, pressure applied to the spray boom deflects internal valve systems to eject fluid when desired. Then, when spraying is discontinued, collapsing internal pressure results in automatic sealing of the spray valve in response to a plunger which closes a suitable internal orifice. Usually some form of sealing gasket is employed therewithin.
Most importantly, prior to the application operation the output rate of the spray boom usually must be selected for the desired job and then appropriately adjusted. Conventional spray booms typically may employ between eight to thirty ejector nozzles per boom, and of course one boom is associated with each airplane wing. Conventionally a plurality of nozzles may be manually removed and plugged with the use of common hand tools such as wrenches and the like to vary application flow rates. Alternatively a series connected valve may be coupled in line with each of the ejector nozzle pipes, and subsequent adjustment of such valves may vary the application rate. Where flow rate is selected by removing (or adding) nozzles, a great deal of valuable time is consumed.
Where conventional, manually adjustable in-line valves are used for flow rate control operational reliability is decreased, and aerodynamic drag may be disadvantageously increased to the detriment of fuel economy and flight characteristics of the airplane. In-line valves may also suffer from dissimilar metal reactions resulting in degradation of structural integrity. This is virtually insured by chemical reaction with the fluids passed through the valves. In order to clean such systems high pressure water must be applied therethrough, and residue and build-up of unwanted chemical residue is an inevitable consequence. Usually total cleaning requires the total removal of the valve. Repeated tightening and loosening of threaded metallic fittings, as will be appreciated by those skilled in the art, often leads to mechanical failure. For example, virtually inevitably some threaded orifice on the spray boom assembly will become "stripped" and concomitant possibly environmentally degrading leakage will almost inevitably occur.
Hence it is my opinion that a valve assembly which may be quick-fitted to existing spray booms, manifolds and the like, and which may be quickly manually flipped between desired operative positions without the use of hand tools is advantageous and necessary.